Surgical instruments, such as scalpels, are used to make an incision in the skin, enabling insertion of devices whose purpose is to deliver various substances to the body. In order to minimize the size of the incision, a guidewire is inserted into the body cavity and instruments can be reliably advanced over the guidewire and into the body cavity for proper placement. This method is known as the “Seldinger Technique.” In many circumstances, the guidewire incision needs to be widened in order to accommodate larger medical devices such as a trocar or catheter. The enlargement is typically done by hand which may lead to an imprecise or larger than needed cut. Therefore, a need clearly exists for a surgical instrument capable of using the guidewire to aid a surgical device, such as a scalpel, in making a more precise incision